Head mounted displays and binoculars are examples of binocular viewing systems in which there is an optical system for each of a user's two eyes to view a scene. There is an inter-pupillary distance between the pupils of the two eyes, estimates of which show the distance varies by about 25 to 30 mm for adults. In the case of head mounted, mixed reality displays, if the optical axis for each optical system is not aligned with the respective eye, the user may have difficulty fusing three-dimensional (3D) content properly or can suffer from eye strain or headaches as muscles of the user's natural vision system. With binocular viewing devices like binoculars and binocular telescopes, a user manually adjusts the position of each optical system in an eyepiece by trial and error to get a clear binocular view, which may take a few minutes.